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/* vi: set sw=4 ts=4: */
/* pidfile.c
*
* Functions to assist in the writing and removing of pidfiles.
*
* Russ Dill <Russ.Dill@asu.edu> September 2001
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include "common.h"
#include "pidfile.h"
static char *saved_pidfile;
static void pidfile_delete(void)
{
if (saved_pidfile) unlink(saved_pidfile);
}
int pidfile_acquire(const char *pidfile)
{
int pid_fd;
if (!pidfile) return -1;
pid_fd = open(pidfile, O_CREAT | O_WRONLY, 0644);
if (pid_fd < 0) {
bb_perror_msg("unable to open pidfile %s", pidfile);
} else {
lockf(pid_fd, F_LOCK, 0);
if (!saved_pidfile)
atexit(pidfile_delete);
saved_pidfile = (char *) pidfile;
}
return pid_fd;
}
void pidfile_write_release(int pid_fd)
{
FILE *out;
if (pid_fd < 0) return;
out = fdopen(pid_fd, "w");
if (out) {
fprintf(out, "%d\n", getpid());
fclose(out);
}
lockf(pid_fd, F_UNLCK, 0);
close(pid_fd);
}
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